<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <meta name="description" content="study project" />
  <title>React App</title>
  <script>
    window.performanceObj = {
      whiteScreenTime: new Date() - performance.timing.navigationStart
    }
  </script>
</head>

<body>
  <div id="root">321</div>
</body>

</html>